The present invention relates to combustion turbine engines, and particularly to combustion turbine engines employing two turbines. More particularly, the present invention relates to a modular power turbine driving a rotating device.
Combustion turbine engines are compact prime movers that are easily adapted to drive many different devices (e.g., generators, pumps, compressors, etc.). To operate most efficiently, the turbine of the combustion turbine engine rotates at a high rotational speed relative to most mechanical devices operable by the turbine. For example, a synchronous generator typically rotates at 3600 RPM or 1800 RPM to generate 60 Hz electricity. If 50 Hz is desired, the generator must rotate at 3000 RPM or 1500 RPM. Other turbine-engines use a high-speed generator that produces a high-frequency output. Additional equipment, namely a rectifier and an inverter, then convert the electricity to a more useable form. Furthermore, screw pumps, as well as other mechanical devices, often operate at a speed between the speed of a synchronous generator and the power turbine. To drive these devices requires a gearbox or a turbine that efficiently operates at the lower speed. Each device driven by a turbine requires a turbine design or gearbox design that accommodates the desired operating speed of the driven component.
The high-operating speed of the turbine requires that it be dynamically stable at all operating speeds and under all load conditions. Small imbalances, loads, or vibration can be detrimental to the operation of the turbine.
According to the present invention a power turbine assembly includes a turbine rotor and a plurality of turbine blades mounted to the rotor and adapted to rotate the rotor in response to a flow of hot gas over the blades. The assembly also includes a support structure having a journal bearing and at least one other bearing supporting the rotor for rotation. The journal bearing has a proximal end and a distal end with respect to the turbine blades. A supply of lubricant communicates with the journal bearing to provide lubricant between the rotor and an inner surface of the journal bearing, the lubricant damps rotational frequencies of the rotor and creates a temperature gradient from greater than about 1000xc2x0 F. at the blades to less than about 350xc2x0 F. at the distal end.
The invention also provides a power turbine assembly including a high-speed turbine rotor having a turbine end and a plurality of turbine blades mounted to the turbine end of the rotor and adapted to rotate the rotor in response to a flow of hot gas over said blades. The assembly also includes a sleeve connected to the rotor, a journal bearing supporting the turbine end of the rotor, and a supply of lubricant communicating with the journal bearing. The assembly provides lubricant between the rotor and the journal bearing, the lubricant substantially damps the vibration of the turbine rotor.
In another embodiment, the invention provides a structure for supporting a combustion turbine rotor for rotation above about 25,000 RPM, and to support the rotor for thrust. The structure includes a sleeve having a drive gear connected to the turbine rotor and a housing defining a first support, a second support, and a lubrication flow path. The lubrication flow path receives a flow of lubricant from an inlet and distributes the flow of lubricant to the first support, the second support, and the drive gear. A journal bearing is connected to the first support to support a first end of the turbine rotor for rotation and a second bearing is connected to the second support to support a second end of the turbine rotor for rotation and to support the thrust load of the rotor.
In yet another embodiment, the invention provides a speed reducing cartridge for interfacing between a high-speed rotating turbine rotor and a lower speed rotating element. The cartridge includes a power turbine cartridge having a journal bearing and a second bearing axially aligned with the journal bearing. The bearings support the turbine rotor for rotation about a first axis. The power turbine cartridge is supported by the speed reducing cartridge. A drive gear is connected to the turbine rotor and a driven gear is connected to the lower speed rotating element. A driven component housing supports the lower speed rotating element for rotation about a second axis. The driven component housing is supported by the speed reducing cartridge such that the drive gear and driven gear engage one another with a backlash. An adjusting assembly interconnects the power turbine cartridge and the speed-reducing cartridge and is movable to adjust the backlash between the drive gear and the driven gear.
The invention further provides a method of controlling heat flow between a high-temperature region and a precision aligned region of a high-speed rotating shaft. The method includes the acts of providing a housing having a journal bearing support and supporting the high-speed shaft for rotation using the journal bearing such that the high-temperature region is adjacent the journal bearing. The method also includes the acts of introducing a flow of lubricant to the journal bearing to provide lubrication between the bearing and the shaft and to provide cooling to the bearing and the shaft and maintaining the precision aligned region of the high-speed rotating shaft below 350xc2x0 F.
In yet another construction, the invention provides a method of supporting and aligning a high-speed turbine rotor having a drive gear with a lower speed rotor having a driven gear such that the high-speed turbine rotor is able to drive the lower speed rotor. The method includes the acts of providing a speed reducing cartridge and supporting the high-speed turbine rotor within a housing for rotation about a first axis, the housing including a journal bearing and a non-journal bearing supporting the turbine rotor for rotation. The method also includes the acts of supporting the lower speed rotor within the speed reducing cartridge such that the lower speed rotor is rotatable about a second axis and interconnecting the housing and the speed reducing cartridge with an adjusting member such that the first axis is offset a distance from the second axis. In addition, the method includes the acts of engaging the drive gear and the driven gear such that a backlash between the gears is present and adjusting the adjusting member to change the distance between the first axis and the second axis to achieve a desired backlash.
Additional features and advantages will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.